The present invention relates to a position-measuring device or sensor for cylinder-and-piston arrangements.
A position sensor of this kind, intended to indicate the position of a piston in the cylinder of a cylinder-and-piston arrangement in a braking system has been known, for example, from DE 100 53 995 A1. In the described arrangement, a hydraulic sensor cylinder is provided with a Hall element, the Hall sensor being inserted in the cylinder wall and a magnetic region being arranged in the cylinder-and-piston arrangement so that the movement of the piston in the cylinder will cause the Hall element to respond. A cylinder-and-piston arrangement wherein the position of the piston is sensed by means of Hall sensors has likewise been known From EP 0 536 926 B1.
A position-measuring device for fluidic cylinders comprising a long measuring coil, designed as an eddy-current long-distance sensor, has been disclosed in DE 202 05 822 U1.
It has further been known to detect the position of a piston by capacitive sensors. An actuator cylinder comprising a sensor for determining the position of the piston by means of capacitive sensors has been known from DE 44 10 363 A1.
Now, it is necessary in many cases to change or adjust the end or stop positions of fluidic cylinder-and-piston arrangements, for example during start-up or operation of the system. To this end, some of the known cylinder-and-piston arrangements have switching elements mounted in a groove in a cylinder profile, for example. In order to adjust a given position, the switching elements are displaced in the groove of the cylinder profile.
Apart from the necessity to effect the adjustment manually, a further disadvantage of an arrangement of this kind is seen in the fissured surface of the cylinder, resulting from the particular structure, which practically excludes the use of such an arrangement in areas where higher demands are placed on hygiene, for example in the foodstuff or pharmaceutical industries.